Multiplex channel repeater system



April 15, 1941. A. F. CONNERY 2,238,248

MULTIPLEX CHANNEL REPEATER SYSTEM Filed April 2-9, 1937 r 2 Sheets-Sheet 2 INVENTOR 4405/? E co/v/vm ATTORNEY E @H howl d 6. 2. m8 1 1 l 1 m at U mm t 5. I J R .8 u a a 5 V L 8 a dd m H a (a Em we Ekug llll 1| L If E Patented Apr. 15, 1941 2,238,248 MULTIPLEX CHANNEL REPEATER SYSTEM Alder F. Connery,

Brooklyn, N. Y., assignor to All America Cables, Incorporated, New York, N. Y., a corporation of New York Application April 29, 1937, Serial No. 139,693

11 Claims.

My invention relates to multiplex channel repeater systems and is particularly directed to multiplex systems which will make it possible to repeat signals received over one multiplex channel into another multiplex channel when said channels operate at different speeds.

The system of my invention makes it possible to repeat the five-unit signals from one channel into another regardless of differences in speed of the channels. could be used to make up a direct trafiic channel by joining two or more multiplex channels in tandem. Suppose, for example, that a New York-Chicago channel operating at fifty words per minute is to be connected at Chicago with a channel of a Chicago-L Angeles circuit which is being operated at forty-eight words per minute. A pair of channel repeater units will be necessary at Chicago, one to repeat the westbound signals and the other the eastbound signals. In the eastward direction the channel repeater at Chicago will automatically send out an occasional blank signal so that the average rate of transmission over the Chicago-New York section will be just forty-eight words per minute. Thus the New York printer will receive a blank signal once in about every twenty-four characters.

In the westward direction, if New York were to send steadily the signals would pile up in the Chicago channel repeater. To avoid this I propose to equip the operating channel at New York with a piece of auxiliary transmitter equipment which will cause the New York transmitter to send out a blank signal at intervals to prevent this undesirable piling up of the signals. In the case of the New York-Los Angeles channel as indicated above, it would be necessary to adjust the transmitter at the New York station, so that it will pause for the duration of one signal at least once in every twenty-four characters.

My invention is not only suitable for interconnecting multiplex channels, but it may also be used to interconnect a start-stop extension cirsuit with a multiplex channel.

Since connection between a transmitter of a given speed feeding into a channel and other channels of much clifierent, lower speeds may at times be desirable, it is preferable to have the auxiliary equipment at the transmitter adjustable so that the frequency of repetition of the blank signals may be varied between quite wide limits. In case that it is necessary to join together a couple of channels and start trafiic moving immediately when the differences in Several of these repeaters,

speed are not known at the terminal station, such adjustable devices are particularly useful. The terminal station may then adjust the transmitter attachment so that the transmitter is held up at very frequent intervals, and later may adjust for maximum channel efficiency.

A number of these units may be provided at each of the larger relay stations in a system and be provided with connections to the second channels of all multiplexes at the station. Suitable switching means may be provided so that the second channel of any multiplex can be quickly connected into the second channel of any other multiplex. Thus if the regular channel circuit between any offices should be interrupted it would be a simple matter to set up an emergency channel via some multiplex channels and thus reduce delays, errors and the cost of rerouting messages.

It is an object of my invention to provide a multiplex system to accomplish the results set forth in the preceding paragraphs.

It is a further object of my invention to provide an auxiliary circuit at the transmitter to permit ready adjustment for transmission of periodic blank pulses.

It is a further object of my invention to provide a system which operates under control of the normal 6th pulse of transmitting stations to interrupt the operation of the transmitter under control of the number of repetitions of said pulse.

It is a further object of my invention to provide a multiplex channel repeater which will operate to give sufiicient impulse storage for enicient operation of the repeater between channels operating at different speeds.

It is a still further object of my invention to provide a means at the repeater for automatically maintaining the transmitting contact of the repeater in a lagging relation with respect to the receiving contact.

Other objects and uses of the invention will present themselves upon reading of the particular description in connection with the illustrating drawings.

An example of the one embodiment of my invention is given in the accompanying drawings, in which- Fig. 1 illustrates diagrammatically one type of auxiliary equipment for controlling the transmitter, and

Fig. 2 illustrates one form of repeater system which may be used in connection with the transmitter of Fig. l to couple together two channels of different operating speeds.

Turning now to Fig. 1, reference character I indicates the transmitter equipment which may be the usual printer telegraph transmitter connected to the usual five distributor contacts 3, 5, 1, 9, I I. This transmitter may be of any desired type such as a tape controlled transmitter or a keyboard controlled transmitter. The usual distributor ring I3 is connected to transmission line I5 and the brush I1 serves to impress the signal pulses upon the transmission line. The usual 6th pulse or control pulse contact I9 cooperating with the ring 2| and the brush 23 is connected with the transmitter operating magnet 25 in the usual manner. The auxiliary transmitter equipment is shown at the right of Fig. 1, enclosed in the dotted line 2. A lead 21 connected to the normal operating magnet lead is connected to a relay 29. Relay 29 is operated each time that transmitter operating magnet 25 is energized. A control tube 3| is provided with a grid condenser 33 initially charged negatively so as to bias the tube to cut-off. Said condenser has a fixed capacity which may be relatively large, for example in the neighborhood of one-half microfarad. A variable condenser 35 of much smaller capacity is connected by way of back contact 39 of relay 29 to a positive potential source when relay 29 is unenergized. By reason of its small capacity condenser 35 is quickly charged to its full voltage. Each time relay 29 is energized the relay contact is made with front contact 32, and the charged condenser 35, transferring the charge to condenser 33. Since condenser 33 is much larger than condenser 35, each positive impulse transferred upon energization of relay 29 only slightly raises the potential on condenser 33. Accordingly, a large number of charges from condenser 35 must be transferred to condenser 33 before the grid of tube 3| is raised to a sufficient potential to render the tube conductive and energize relay 31. When surficient potential has been built up on condenser 33, relay 31 operates removing its contact tongue from back contact 38, removing the shunt 39 from the windings of relay 31, and closing the..

front contact 49 connecting positive potential to line 4 I. When relay 29 is again energized closing contact 43, a circuit is established from the source of positive potential through line 4|, contact 43, contact 45 of relay 41, the winding of relay 49, and thence to a source of negative potential through contact 59 of relay 5|. Auto stop magnet 53 is energized through the left contact 55 of relay 49, stopping the operation of the transmitter I. The left winding 51 of relay 41.

is brought into circuit through the closing of contact 59 of relay 49. However, relay 41 will not yet operate since the left winding is short circuited through contact 45 and the associated connections. When the 6th pulse is finished deenergizing relay 29, relay 49 will remain operated due to the locking circuit through contact 59 and winding 51 of relay 41. The transmitter in the meantime remains locked and a blank is being transmitted. Relay 41, move its left armature into engagement with contact 46. When the next 6th pulse occurs a circuit will be established from the source of positive potential, contact 6| of relay 41, contact however, operates toL L 43 of relay 29, contact 46 of relay 41, the winding of relay 5|, and the right hand winding 63 of relay 41, to a negative potential source. Relays 41 and 5| are, for the time being, in energized condition. Operation of relay 5| opens the contact 59, removing the locking circuit from relay:

49, and deenergizing the auto stop magnet 53 through the opening of contact 55. At the same time that contact 59 is opened, contact 65 is closed, connecting the source of negative potential to condenser 33 and the grid of tube 3|, thus deenergizing relay 31. When the 6th pulse is ended relay 29 will be deenergized, breaking the circuit through the winding of relay 5| at contact 43 and likewise the right Winding 33 of relay 41, restoring these relays to normal. The control circuit is thus returned to normal and is ready to repeat another cycle similar to the one just described.

If less frequent stopping of the transmitter is desired, variable condenser 35 may be decreased in capacity. This will decrease the magnitude of positive charge transferred to the condenser 33 at each 6th pulse, and thus cause less frequent operation of the stopping circuit. If greater frequency of interruption is desired, the capacity of condenser 35 may be increased.

While the circuit described above provides a convenient means for automatic stopping of the transmitter to provide desired spacing, it is clear that other modifications and circuits could be used for this purpose. For example, switches could be arranged to operate at a particular number of pulses to interrupt the operation of the transmitter. Likewise some mechanical means such as, for example, gearing mechanism with adjustable gear ratios could be provided to furnish an adjustable interruption of the transmitter.

The repeater mechanism shown in Fig. 2 will now be described. Transmission line I5, which may be the line connected to the transmitter illustrated in Fig. 1, is connected through the repeater relay 1| to ground. This repeater relay serves to transfer the marking and spacing impulses from the transmitter through line 13 to the contact ring 15 of the receiving distributor. The usual character pulse receiving contacts 11, 19, BI, 83, are periodically coupled by distributor brush 81 to the contact ring to transfer the character pulses from the line. The usual 6th pulse contact is shown at 89 cooperating with ring 9| connected to a positive potential source by brush 93. The receiving distributor contacts 11-85 are coupled to the usual receiving relays 91, 99, IUI, I93, I95, respectively, and a common return lead I91 of said receiving relays is connected to the left winding of relay I99 as shown. A multiple contact receiving switch indicated generally at serves to transfer the received character impulses to suitable storing means such as condensers. The receiving switch as shown is provided with five contacts and five condensers associated with the respective contacts. However, this is shown merely by way of illustration as four contact switches would be entirely satisfactory for the operation of the system. One switch unit H1, H9, I2I, I23, I25 is provided to cooperate with each of the receiving relays 91|05, respectively. Each of the switches is provided with a contact arm to cooperate with the various contacts arranged around the switch and to transfer the signal impulse to the particular storing condenser to be charged depending upon the position of the receiving switch contact arm. When the 6th pulse is received a circuit is completed through contact 89, contact I21 of relay I09, through contact |3I of relay I29, and through operating magnet I33 of receiving switch I. The contacts I35 and |3| of relay I29 are make-before-break type and once relay I29 is operated it is no longer necessary to keep relay I09 operated. Accordingly, contact I31 of relay I 29 shorts out the locking winding of relay I99 thus restoring the relay to normal. When the 6th pulse is endedthe circuit of relay I29 is opened and it also restores to normal, and operating magnet I93 is deenergized. Upon cleenergization of magnet I33 the contact arms or wipers of switches II'II25 are advanced one step through the medium of suitable mechanism such as the usual pawl and ratchet devices. Other letters are sent through contacts II-85 in a similar manner and are stored in storing condensers in regular sequence. When a blank signal is sent due to the stopping of transmitter I, none of the receiving relays will operate and therefore relay I99 will not be energized and contact lil will remain open. The 6th pulse circuit will therefore be open and no signals will be stored and the switch will not advance to the next point.

A sending switch I M which is substantially identical with the receiving switch III, is provided for transferring the stored received signals to the transmitting distributor contact. This transmitting switch is provided with five units Ml, I99, Hill, I93, 595, respectively, corresponding with the receiving switch units II'I-I25, and each of these switch units is provided with a rotary contact arm or wiper which is connected to suitable lead lines with the transmitting relays Iel'l, I59, ltl, i633, I95, respectively, corresponding with the switching elements, and which serve to transfer the residual character signal will look through the locking windings and there- I by properly polarize the transmitting contacts of impulses to the corresponding transmitting distributor contacts I91, I99, Ill, H3, tively. and through brush ring M9 to the transmission line I 8| for transmission to a finther station. The receiving station may comprise the usual receiving distributor I75, respec- Ill and distributor and a suitable receiving apparatus. A 6th pulse contact Illil cooperates With a ring I85 through brush Hill to control the transmitter switch operating magnet I89 which is associated with suitable control mechanism such as pawl and ratchet means to control the rotation of the switch wiper arms. When the 6th pulse contact is closed a circuit is completed through contact I ill of differential relay 93, through the right half of.

the winding of relay I93, and through the winding of relay I95 to a source of negative potential. Another circuit is established-through conductor I91, contact I99 of relay 2!, through the left half of the differential winding on relay I93 and thence to the winding of .relay I955. The currents through the two windings on relay I93 are in opposition and relay 693 is therefore not operated. When relay I95 is energized positive potential is removed from contact 203 of relay I95, thus opening the transmitter relay locking circuit and restoring any of the transmitting relays that may have been in operated position, to normal. The operation of relay I95 serves to energize the operating magnet I 89 of transmitting switch I il through contact 295. When the 6th pulse is ended relay I95 will restore to normal, thus restoring the locking potential to the tongues of the transmitting relays through contact 295i, and at the same time deenergizing switch operating magnet I 69 and serving to advance the wipers of switches I lll to the next contact point. The storing condensers connected to the next receiving point will then discharge into the operating windings of the transmitting relays and the relays will be actuated properly to transmit the succeeding signals; The

transmitting relays which have been actuated the transmitting distributor to send the proper signals.

In order to properly operate, the transmitting switch Wipers must at all times remain behind the receiving switch wipers. In order to assure that this relation is maintained, additional switch units 297 and 299 are provided in the receiving switch and the transmitting switch, respectively. These switch units have. the same number of contacts as the regular distributing switches and their wiper arms are mechanically connected to operate in synchronism with the wipers of the other switches. The wiper arm of receiving switch unit 29'! is supplied with a positive potential and the wiper arm of transmitting switch unit 299 is connected to the winding of relay 29I to a source of negative potential. The corresponding contacts of the units 297 and 299 are directly connected together by conductors. In the event that the transmitting switch overtakes the receiving switch a circuit is completed from the positive battery through the contact of switch 201 and the contact of switch 299 and through the winding of relay 29!, thus energizing the re lay. Operation of relay 2M opens the contact I99 so upon receipt of the 6th pulse only the right half of the winding on relay I93 will be energized and the relay will therefore operate. Operation of relay I93 connects the winding of relay I 95 through contact 2 and resistance 2i 3 to a source of positive potential, thus looking relay I95 in operative removing locking current from the transmitting relays. If, during the period that no 6th pulse is being received from the transmitting distributor relay 29I should become deenergized due to the receiving switch advancing, there will be no change in the condition of relay I95 or the transmitting switch. Accordingly, a blank signal will be transmitted. As soon, however, as the 6th pulse is received from the transmitting distributor there will be again equal currents in the two windings of relay I93 since contact I99 has been restored, and relay I93 will accordingly restore to normal. At the end of the 6th pulse, relay I95 will also restore to normal and the transmitting switch will advance to the next set of points in the normal manner.

During idle periods when no traffic is being transmitted through the repeater, all the relays and switches will be idle and therefore not subject to wear. During such idle periods relays I95, ZIII' and I93 will be energized and the transmitting switch I99 will also be energized. To prevent overheating of this operating magnet I89 and to economize on power, switch 255 is provided to be controlled by the operating magnet so as to open and insert resistance fill in circuit whenever the operating magnet has reached the limit of its stroke.

While the above description of the repeater circuit has been made with reference to the embodiments illustrated in Fig. 2, it is clear that various modifications may be made in this circult without altering the essential operation of the same. For example, a series of relays operating in sequence upon reception of the 6th pulse impulses could be used to establish the various line connections to the storing condensers and to the transmitting distributor contacts in place of the rotary switches controlled by such me chanical means as the pawl and ratchet illus trated. It is clear that other modifications will position, and thereby also be obvious to replace various elements of the system as shown and accordingly I do not wish to limit my invention to this particular embodiment as shown.

From the specific detailed description given of the circuit above, the operation of the system according to my invention is quite clear. However, a brief resume of the operation will more clearly fix in mind the operation of this system. Accordingly, transmitter l is operated to send code impulse characters over line 55, and the repeater illustrated in Fig. 2 is connected to repeat these signals into another line which is operating at a different transmission speed. In event that the transmission speed of the transmitter feeding into line I5 is greater than that of the receiver connected to line Isl, an auxiliary means operating as disclosed in Fig. 1, may be used with the transmitter to periodically stop the operation of the transmitter so that the number of characters transmitted per minute will average the same or less than those which can be received over line HM. Thus, high speed transmitter sig nals may be repeated directly into a lower speed line. The condenser 35 in the auxiliary equipment may be adjusted so as to interrupt the transmitter the proper number of times to provide for matching of the number of transmitted characters and the operating speed of the receiving line. The blank signals which occur due to the stopping of the transmitting mechanism will not operate the receiving switch relay I33, and accordingly will not advance the switch wipers and the transmitting switch will accordingly operate the same way as if the two lines coupled were synchronized as received. In event that the transmitting switch wipers overtake the receiving switch wipers, the transmitting contact will be rendered inoperative as described above,

so that the proper displacement between wipers will be maintained.

In event that signals are to be transmitted from a channel of low speed into one of higher speed, the auxiliary control may be disconnected from the transmitter. The normal control mechanism of the repeater switches will serve then to interrupt the sending switch operation each time that this switch tends to overtake the receiving switch and will accordingly automatically send a blank signal over the line, which blank signal will inherently occur at intervals so as to equalize the number of characters transmitted over the lines connected to the repeater.

From the above description it can be readily seen that my invention provides a very flexible unit for use in multiplex repeaters and accordingly is extremely useful. By use of this system multiplex lines may be coupled in tandem even though their speeds of operation are quite different.

While I have described my invention with reference to the particular illustrations shown in the drawings, I do not desire to limit myself to this particular disclosure but intend to cover all features of the circuit and combination in equivalent structure as defined in the appended claims.

What I claim is:

1. In combination, a multiple telegraph transmitter operable to transmit signals composed of groups of impulses in succession at a predetermined speed, means for automatically interrupting the operation of said transmitter at predetermined intervals corresponding to the transmission of a predetermined number of groups of signal impulses, a transmission line operatively,

associated with said transmitter, a second transmission line connected to apparatus responsive to received signal impulses at a speed lower than said predetermined speed, and repeating means provided with storage means for storing a variable number of signals interconnecting said lines for repeating said signals from said transmitter to said apparatus.

2. In a multiplex telegraph system, a telegraph transmitter for transmitting signals comprising groups of a predetermined number of impulses, a line associated with said transmitter, a retransmitting means in said line, comprising a receiv ing distributor connected to said line, a transmitting distributor connected to a second line, impulse storage means for storing a, variable number of said impulse groups, means interposed between said distributors for impressing said impulse groups received on said receiving distributor from said transmitter on said impulse storing means, and means'for applying said stored impulse groups to said transmitting distributor at intervals depending upon the difference in speed of the distributor brushes, and means at said transmitter for interrupting the normal operation of said transmitter for a fixed period at intervals dependent upon said difierence in speed.

3. A telegraph system according to claim 2, in which means are provided under control of said transmitting distributor for maintaining said impulse applying means in a lagging relation with respect to said impulse impressing means.

4. In a telegraph transmitter, a local transmitter control means, means for transmitting control impulses to a local point, means operative upon transmission of each said control impulse for applying said predetermined electric charge upon a local transmitter control means, and means responsive to the accumulation of a predetermined number of said charges upon said local transmitter control means to interrupt the normal operation of said transmitter for a fixed period of time.

5. A telegraph transmitter as claimed in claim l, in which said transmitter control means comprises a vacuum tube normally biased to cutoff and provided with a storage condenser, and

said means for applying a predetermined charge comprises a condenser normally subject to a positive charge, and a relay operative under control of said control impulses for applying the positive charge to said storage condenser.

6. A channel repeater, comprising a receiving distributor for the channel character impulses. relays and rotary switch means associated with said distributor for applying said character impulses to impulse storage means, a plurality of contacts on said switch means, means responsive to a control impulse for advancing said rotary switch means to cooperative relation with another impulse storage means, a sending switch means provided with the same number of contacts as said rotary switch, said contacts being connected to said impulse storage means, a transmitting distributor, rotary means cooperating with said contacts for impressing said stored signals on said transmitting distributor, a control contact on said transmitting distributor, means responsive to connection with said control contacts to advance said rotary means to one step, and means operative with said rotary switch and said sending switch to maintain said sending switch rotary means in a lagging relation relative to said rotary means.

7. A multiplex telegraph transmitting system for interconnecting circuits of diiferent transmission speeds, comprising a transmitter operable at constant speed, a distributor for transmitting impulse groups from said transmitter, transmission means for transferring said impulse groups to a distant point, means for receiving said impulse groups and retransmitting said signals unchanged in number over a second transmission means at a speed lower from the transmitter speed, and means cooperating with said transmitter to interrupt normal operation of said transmitter for a fixed period of time at predetermined intervals whereby the average working speeds in the two lines will be the same.

8. A telegraph system in accordance with claim '7, in which said receiving and retransmitting means comprises storage means for said signal impulses, and means for maintaining a definite time relation between said receiving means and said retransmitting means.

9. A multiplex telegraph system for communicating between two points regardless of differences in speed of transmission, comprising a transmitter operable to transmit a series of character signals each represented by a predetermined number of elements at a predetermined speed, means for adjustably interrupting the normal operation of said transmitter at predetermined intervals, a transmission line operatively associated with said transmitter whereby said signals are impressed on said line at said predetermined speed by said transmitter and for intervals determined by said interrupting device, a second transmission line connected to apparatus operable to receive said character signals at a slower speed than said predetermined speed, repeating means interconnecting said transmission lines, said repeating means comprising means for storing signals received from said transmitter, and means for applying said stored signals with said predetermined number of elements to said second transmission line at proper speed for receipt by said apparatus.

10. A multiplex telegraph system according to claim 9, further comprising means in said repeater for maintaining said means for applying the stored signals to the line in lagging relation to the means for storing said signals.

11. A multiplex telegraph system for communieating between two points regardless of differences in speed of transmission, comprising a transmitter operable to transmit successive character signals comprising a predetermined number of impulses at a predetermined speed, means for adjustably interrupting the operation of said transmitter at predetermined intervals, a transmission line operatively associated with said transmitter whereby said character signals are impressed on said line at a speed determined by said transmitter and for intervals determined by said interrupting device, a repeater coupled to said transmission line, said repeater comprising a receiving distributor for the impressed signals, receiving switch means for applying all of said impulses of one of said received signals to a signal storage means, means responsive to a control impulse derived from operation of said switch means for applying all of said impulses of subsequent successively received signals to other storage means, a transmitting distributor, and sending switch means operatively associated with said storage means for successively impressing all of the impulses of said stored signals on said transmitting distributor, a second transmission line connected at one end with apparatus operating to receive signals comprising said predetermined number of impulses at a slower speed than they are transmitted by said transmitter, and operatively associated at the other end said transmitting distributor, and means operative under joint control of said receiving switch and said sending switch for maintaining said sending switch in a lagging relation relative to said receiving switch.

ALDER F. CONNERY. 

